Heavy alcohol intake is known to damage the ability of the lung to protect itself from infections such as pneumonia and bronchitis. The lung's first line of defense against such infection is to trap inhaled particles and propel them out of the lung using the mucociliary apparatus. In a healthy individual, this apparatus produces mucus, which traps inhaled particles, and is then propelled out of the lung by cilia, the fingerlike projections of the lung lining. Damage to cilia results in pneumonia and loss of lung function. We have established that alcohol profoundly injures this delicate mucociliary apparatus by altering critical proteins called kinases. Two of these kinases, PKA and PKG, are well-described molecules that regulate cell functions including lung cilia. Our experiments in alcohol-fed mice have demonstrated that alcohol profoundly impairs the function of these kinases, resulting in a loss of the normal "fight or flight" responsiveness of the mucociliary apparatus in a manner that requires the production of nitric oxide. While we have established that alcohol causes this problem, we do not know how long it persists if alcohol is removed. We also do not know exactly how alcohol alters these important kinase-dependent functions in cilia. This leads us to hypothesize that: Chronic alcohol exposure causes time-dependent and reversible impairment of mucociliary function by altering specific regulatory proteins in airway epithelial cilia. In this proposal, we propose experiments designed to answer two questions: 1. Is alcohol-driven impairment of mucociliary function preventable or reversible? and 2. Which cilia proteins are affected by alcohol? We propose to answer these questions through experiments proposed in four specific aims: 1. Characterize the time course and reversibility of chronic alcohol impairment of mucociliary function;2. Define the signaling pathways and role that oxidant stress plays in alcohol-mediated nitric oxide-dependent regulation of ciliary motility, 3. Determine the kinase phosphorylation targets present on cilia that are altered by alcohol exposure;and 4. Identify the molecular determinants of alcohol-mediated cilia injury using isolated cilia models. Although we have learned much about the impact and mechanisms of alcohol injury to mucociliary function, the studies we propose will extend our knowledge into how this may be prevented or treated and exactly how alcohol alters molecules critical for cilia function and lung health.